Light Emitting Structure, Display Device Including a Light Emitting Structure and Method of Manufacturing a Display Device Including a Light Emitting Structure

ABSTRACT

A light emitting structure includes a first hole injection layer, a first organic light emitting layer, a charge generation layer, a second hole injection layer, a second organic light emitting layer, an electron transfer layer, and a blocking member. The light emitting structure has first, second, and third sub-pixel regions. The first organic light emitting layer may be on the first hole injection layer. The charge generation layer may be on the first organic light emitting layer. The second hole injection layer may be on the charge generation layer. The second organic light emitting layer may be on the second hole injection layer. The electron transfer layer may be on the second organic light emitting layer. The blocking member may be at at least one of the first to the third sub-pixel regions.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to Korean patentApplication No. 10-2011-0063644, filed on Jun. 29, 2011, the disclosureof which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Field

Example embodiments of the present invention relate to a light emittingstructure, a display device including a light emitting structure, and amethod of manufacturing a display device including a light emittingstructure.

2. Description of Related Art

An organic light emitting display (OLED) device displays informationsuch as images and characters using light generated from an organiclayer therein. As for the organic light emitting display device, lightmay be generated by combination of holes from an anode and electronsfrom a cathode occurred at the organic layer between the anode and thecathode. In various display devices such as a liquid crystal display(LCD) device, a plasma display (PDP) device, and a field emissiondisplay (FED) device, the organic light emitting display device hasfeatures such as wide viewing angle, fast response time, thin thickness,and low power consumption, so that the organic light emitting displaydevice is widely employed in various electrical and electronicapparatuses, for example, televisions, monitors, mobile communicationdevices, MP3 players, portable display devices, etc. Recently, theorganic light emitting display device has been regarded as one of themost promising next-generation display devices.

In a conventional organic light emitting display device, electrons andholes provided from electrodes may be recombined at an organic layer togenerate excitons, so that light having a specific wavelength may begenerated by the energy of the excitons to display images. Although theorganic light emitting display device may have a single layer structure,a multi-layer structure, or a color conversion structure, themulti-layer structure is widely applied in the organic light emittingdisplay device. The multi-layer structure may include organic layersthat emit red light, green light, and blue light, respectively, and thusred, green, and blue lights may be combined to generate white light.However, the conventional organic light emitting display may have somedisadvantages such as relatively low functional stability of the organiclayers and low purity of colors of light. Even though a color filter maybe disposed over the organic layers to improve the purity of colors oflight, manufacturing processes may be complicated and also manufacturingcost for the display device may be increased. Further, the conventionalorganic light emitting display device may have low luminance efficiencybecause of the color filter.

SUMMARY

Example embodiments of the present invention are directed toward a lightemitting structure having improved color purity, enhanced colorreproducibility, and increased brightness.

Example embodiments of the present invention are directed toward adisplay device capable of displaying a high resolution image withimproved color purity and enhanced brightness.

Example embodiments of the present invention are directed toward amethod of manufacturing a display device capable of displaying a highresolution image with improved color purity and increased brightness.

According to an example embodiment, a light emitting structure includesa first hole injection layer, a first organic light emitting layer, acharge generation layer, a second hole injection layer, a second organiclight emitting layer, an electron transfer layer, and a blocking member.The light emitting structure may be divided into a first sub-pixelregion, a second sub-pixel region, and a third sub-pixel region. Thefirst organic light emitting layer may be on the first hole injectionlayer. The charge generation layer may be on the first organic lightemitting layer. The second hole injection layer may be on the chargegeneration layer. The second organic light emitting layer may be on thesecond hole injection layer. The electron transfer layer may be on thesecond organic light emitting layer. The blocking member may be at atleast one of the first sub-pixel region, the second sub-pixel region, orthe third sub-pixel region.

In example embodiments, a first optical resonance distance in the firstsub-pixel region, a second optical resonance distance in the secondsub-pixel region, and a third optical resonance distance in the thirdsub-pixel region may be different from each other.

In example embodiments, the light emitting structure may include anoptical distance controlling insulation layer at at least one of thefirst sub-pixel region, the second sub-pixel region, or the thirdsub-pixel region.

In example embodiments, the optical distance controlling insulationlayer may be under the first hole injection layer.

In example embodiments, the optical distance controlling insulationlayer may have different thicknesses in adjacent sub-pixel regions.

In example embodiments, the optical distance controlling insulationlayer may include a material that is the same as that of the first holeinjection layer.

In example embodiments, the first optical resonance distance may beadjusted to generate an optical resonance for a red light emitted fromthe first organic light emitting layer or the second organic lightemitting layer, the second optical resonance distance may be adjusted togenerate an optical resonance for a green light emitted from the firstorganic light emitting layer or the second organic light emitting layer,and the third optical resonance distance may be adjusted to generate anoptical resonance for a blue light emitted from the first organic lightemitting layer or the second organic light emitting layer.

In example embodiments, the first organic light emitting layer mayinclude a blue-light emitting film, and the second organic lightemitting layer may include a green-light emitting film and a red-lightemitting film, or a single light emitting film adapted to emit greenlight and red light.

In example embodiments, the blocking member may be between the secondhole injection layer and the first organic light emitting layer at thefirst sub-pixel region, and the blocking member may be adapted to blocka movement of electrons from the second hole injection layer to thefirst organic light emitting layer at the first sub-pixel region.

In example embodiments, the blocking member may be between the chargegeneration layer and the first organic light emitting layer at the firstsub-pixel region, and the blocking member may be adapted to block amovement of excitons generated at the first organic light emitting layerat the first sub-pixel region.

In example embodiments, the first organic light emitting layer mayinclude a green-light emitting film and a red-light emitting film, or asingle light emitting film adapted to emit green light and red light,and the second organic light emitting layer may include a blue-lightemitting film.

In example embodiments, the blocking member may be between the secondhole injection layer and the second organic light emitting layer at thefirst sub-pixel region, and the blocking member may be adapted to blocka movement of electrons to the second organic light emitting layer atthe first sub-pixel region.

In example embodiments, the blocking member may be between the electrontransfer layer and the second organic light emitting layer at the firstsub-pixel region, and the blocking member may be adapted to block amovement of excitons generated from the second organic light emittinglayer at the first sub-pixel region.

In example embodiments, the blocking member may include an electronblocking layer or an exciton quenching layer.

In example embodiments, the blocking member may include fullerene, apolymer including substituted triarylamine, a carbazole based polymer,

-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)cyclohexane (TAPC),-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)cyclopentane,-   4,4′-(9H-fluoren-9-ylidene)bis[N,N-bis(4-methylphenyl)-benzenamine,-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-4-phenylcyclohexane,-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-4-methylcyclohexane,-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-3-phenylpropane,-   Bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylpenyl)methane,-   Bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)ethane,-   4-(4-Diethylaminophenyl)triphenylmethane,-   4,4′-Bis(4-diethylaminophenyl)diphenylmethane,-   N,N-bis[2,5-dimethyl-4-[(3-methylphenyl)phenylamino]phenyl]-2,5-dimethyl-N′-(3-methy    (phenyl)-N′-phenyl-1,4-benzenediamine,-   4-(9H-carbazol-9-yl)-N,N-bis[4-(9H-carbazol-9-yl)phenyl]-benzenamine    (TCTA),-   4-(3-phenyl-9H-carbazol-9-yl)-N,N-bis[4(3-phenyl-9H-carbazol-9-yl)phenyl]-benzenamine,9,9′-(2,2′-dimethyl[1,1′-biphenyl]-4,4′-diyl)bis-9H-carbazole    (CDBP),-   9,9′-[1,1′-biphenyl]-4,4′-diyl)bis-9H-carbazole (CBP),-   9,9′-(1,3-phenylene)bis-9H-carbazole (mCP),    9,9′-(1,4-phenylene)bis-9H-carbazole,-   9,9′,9″-(1,3,5-benzenetriyl)tris-9H-carbazole,-   9,9′-(1,4-phenylene)bis[N,N,N′,N′-tetraphenyl-9H-carbazole-3,6-diamine,-   9-[4-(9H-carbazol-9-yl)phenyl]-N,N-diphenyl-9H-carbazol-3-amine,-   9,9′-(1,4-phenylene)bis[N,N-diphenyl-9H-carbazol-3-amine,-   9-[4-(9H-carbazol-9-yl)phenyl]-N,N,N′,N′-tetraphenyl-9H-carbazole-3,6-diamine,-   9-phenyl-9H-carbazol, etc.

According to example embodiments, a display device includes a substrate,a first electrode, a light emitting structure, and a second electrode.The substrate may include a first sub-pixel region, a second sub-pixelregion, and a third sub-pixel region. The first electrode may be on thesubstrate. The light emitting structure may be on the first electrode.The light emitting structure may include a blocking member at at leastone of the first sub-pixel region, the second sub-pixel region, or thethird sub-pixel region. The second electrode may be on the lightemitting structure. A first optical resonance distance between the firstelectrode and the second electrode at the first sub-pixel region, asecond optical resonance distance between the first electrode and thesecond electrode at the second sub-pixel region, and a third opticalresonance distance between the first electrode and the second electrodeat the third sub-pixel region may be different from each other.

In example embodiments, the light emitting structure may include a firsthole injection layer, a first organic light emitting layer, a chargegeneration layer, a second hole injection layer, a second organic lightemitting layer, and an electron transfer layer. The first hole injectionlayer may be on the first electrode. The first organic light emittinglayer may be on the first hole injection layer. The charge generationlayer may be on the first organic light emitting layer. The second holeinjection layer may be on the charge generation layer. The secondorganic light emitting layer may be on the second hole injection layer.The electron transfer layer may be on the second organic light emittinglayer.

In example embodiments, the light emitting structure may further includean optical distance controlling insulation layer on the first electrode.The optical distance controlling insulation layer may have differentthicknesses in adjacent sub-pixel regions.

In example embodiments, the first optical resonance distance may beadjusted to generate an optical resonance for a red light emitted fromthe first organic light emitting layer or the second organic lightemitting layer, the second optical resonance distance may be adjusted togenerate an optical resonance for a green light emitted from the firstorganic light emitting layer or the second organic light emitting layer,and the third optical resonance distance may be adjusted to generate anoptical resonance for a blue light emitted from the first organic lightemitting layer or the second organic light emitting layer.

In example embodiments, the first organic light emitting layer mayinclude a blue-light emitting film. The second organic light emittinglayer may include a green-light emitting film and a red-light emittingfilm, or a single light emitting layer adapted to emit green light andred light.

In example embodiments, the blocking member may be between the firsthole injection layer and the first organic light emitting layer at thefirst sub-pixel region, and the blocking member may be adapted to blocka movement of electrons from the first hole injection layer to the firstorganic light emitting layer at the first sub-pixel region.

In example embodiments, the blocking member may be between the chargegeneration layer and the first organic light emitting layer at the firstsub-pixel region, and blocking member may be adapted to block a movementof excitons generated from the first organic light emitting layer at thefirst sub-pixel region.

In example embodiments, the first organic light emitting layer mayinclude a green-light emitting film and a red light-emitting film, or asingle light emitting layer adapted to emit green light and red light.The second organic light emitting layer may include a bluelight-emitting film.

In example embodiments, the blocking member may be between the secondhole injection layer and the second organic light emitting layer at thefirst sub-pixel region, and the blocking member may be adapted to blocka movement of electrons to the second organic light emitting layer atthe first sub-pixel region.

In example embodiments, the blocking member may be between the electrontransfer layer and the second organic light emitting layer at the firstsub-pixel region, and the blocking member may be adapted to block amovement of excitons generated from the second organic light emittinglayer at the first sub-pixel region.

According to example embodiments, there is provided a method ofmanufacturing a display device. In the method, a first electrode may beformed on a substrate. The substrate may have a first sub-pixel region,a second sub-pixel region, and a third sub-pixel region. A lightemitting structure may be formed on the first electrode. The lightemitting structure may include an optical distance controlling layer anda blocking member. A second electrode may be formed on the lightemitting structure. A first optical resonance distance between the firstelectrode and the second electrode at the first sub-pixel region, asecond optical resonance distance between the first electrode and thesecond electrode at the second sub-pixel region, and a third opticalresonance distance between the first electrode and the second electrodeat the third sub-pixel region may be different from each other.

In example embodiments, the optical distance controlling insulationlayer may be formed at at least one of the first sub-pixel region, thesecond sub-pixel region, or the third sub-pixel region.

In example embodiments, forming the optical distance controllinginsulation layer may include forming the optical distance controllinginsulation layer on the first electrode by a laser induced thermalimaging process.

In example embodiments, forming the optical distance controllinginsulation layer may further include laminating a donor substrate on thesubstrate, irradiating a laser beam to at least one region of the donorsubstrate, the at least one region of the donor substrate correspondingto at least one of the first, the second, and the third sub-pixelregions, and removing the donor substrate from the substrate.

In example embodiments, forming the light emitting structure may furtherinclude forming a first organic light emitting layer on the opticaldistance controlling insulation layer, forming a charge generation layeron the first organic light emitting layer, and forming a second organiclight emitting layer on the charge generation layer.

In example embodiments, the blocking member may be between the opticaldistance controlling layer and the first organic light emitting layer atat least one of the first, the second, and the third sub-pixel regions.

In example embodiments, the blocking member may be formed by a laserinduced thermal imaging process.

In example embodiments, forming the blocking member may further includelaminating a donor substrate on the substrate, irradiating a laser beamto at least one region of the donor substrate, the at least one regionof the donor substrate corresponding to at least one of the first, thesecond, and the third sub-pixel regions, and removing the donorsubstrate from the substrate.

In example embodiments, the blocking member may be between the firstorganic light emitting layer and the charge generation layer at at leastone of the first, the second, and the third sub-pixel regions.

In example embodiments, the blocking member may be between the secondorganic light emitting layer and the second electrode at at least one ofthe first, the second, and the third sub-pixel regions.

According to example embodiments, each of sub pixel regions may haveoptical resonance distances which may be substantially different fromeach other, so that lights having different wavelengths may be emittedfrom each of the sub-pixel regions. Therefore, color purity, brightness,and color gamut of a display device may be improved, and a drivingvoltage of the display device may be reduced thereby to extend alifetime of the display device. Further, a blue light emitting layer maybe separated from a red light emitting layer and/or a green lightemitting layer, so that color stability may be improved, and a lifetimeof the blue light emitting layer may be extended. The display device maydisplay high resolution images having high color purity and highbrightness without a color filter. In the manufacturing process of thedisplay device, additional layers such as the color filter may not needto be formed, and thus a cost of the manufacturing process may bereduced, and the manufacturing process may be simplified. Further, thecolor filter may not be disposed on the light emitting layers, so that areduction of the brightness by the color filter may be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments may be understood in more detail from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a cross-sectional view illustrating a display device having alight emitting structure in accordance with example embodiments;

FIG. 2 is a graph showing peak wavelengths of optical resonances of redlight and blue light depending on a thickness of an electron blockinglayer;

FIG. 3 is a cross-sectional view illustrating a display device having alight emitting structure in accordance with some example embodiments;

FIG. 4 is a cross-sectional view illustrating a display device having alight emitting structure in accordance with some example embodiments;

FIG. 5 is a cross-sectional view illustrating a display device having alight emitting structure in accordance with some example embodiments;

FIG. 6 is a cross-sectional view illustrating a display device having alight emitting structure in accordance with some example embodiments;and

FIGS. 7 to 14 are cross-sectional views illustrating a method ofmanufacturing a display device having a light emitting structure inaccordance with example embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Various example embodiments will be described more fully hereinafterwith reference to the accompanying drawings, in which some exampleembodiments are shown. The present invention may, however, be embodiedin many different forms and should not be construed as limited to theexample embodiments set forth herein. Rather, these example embodimentsare provided so that this description will be thorough and complete, andwill fully convey the scope of the invention to those skilled in theart. In the drawings, the sizes and relative sizes of layers and regionsmay be exaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to,” or “coupled to” another element or layer, itcan be directly on, connected, or coupled to the other element or layer,or one or more intervening elements or layers may be present. When anelement is referred to as being “directly on,” “directly connected to,”or “directly coupled to” another element or layer, there may be nointervening elements or layers present. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third,fourth, etc. may be used herein to describe various elements,components, regions, layers, and/or sections, these elements,components, regions, layers, and/or sections should not be limited bythese terms. These terms are only used to distinguish one element,component, region, layer, or section from another element, component,region, layer, or section. Thus, a first element, component, region,layer, or section discussed below could be termed a second element,component, region, layer, or section without departing from theteachings of the invention.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations), and the spatiallyrelative descriptors used herein are interpreted accordingly.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to limit the invention. Asused herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized example embodiments (and intermediate structures). As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, example embodiments should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature, and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofthe invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

FIG. 1 is a cross-sectional view illustrating a display device having alight emitting structure in accordance with example embodiments.

Referring to FIG. 1, the display device may include a substrate 100, aswitching structure, a first electrode 300, a light emitting structure400, a second electrode 500, etc.

In example embodiments, the display device may include a display regionwhere the light emitting structure 400 may be positioned and anon-display region adjacent to the display region. Further, the displayregion of the display device may include a first sub-pixel region (I), asecond sub-pixel region (II), and a third sub-pixel region (III). Inthis case, the light emitting structure 400 may also have the firstsub-pixel region (I), the second sub-pixel region (II), and the thirdsub-pixel region (III).

The switching structure may be disposed between the substrate 100 andthe first electrode 300, and the light emitting structure 400 may belocated between the first electrode 300 and the second electrode 500. Inthis case, the switching structure may be on the substrate 100.

A buffer layer 110 may be disposed on the substrate 100. The bufferlayer 110 may prevent impurities from being diffused from the substrate100. The buffer layer 110 may improve a flatness of the substrate 100.Further, the buffer layer 110 may reduce a stress generated in a processfor forming the switching structure on the substrate 100. The bufferlayer 110 may include an oxide, a nitride, an oxynitride, etc. Forexample, the buffer layer 110 may have a single layer structure or amulti-layer structure including silicon oxide (SiOx), silicon nitride(SiNx) and/or silicon oxynitride (SiOxNy).

When the display device is an active matrix type, the switchingstructure may be disposed between the substrate 100 and the firstelectrode 300. The switching structure may include a switching deviceand one or more insulation layers. In example embodiments, the switchingdevice may include a thin film transistor having a semiconductor layercontaining, for example, silicon. In some example embodiments, theswitching device may include an oxide semiconductor device having anactive layer containing a semiconductor oxide.

When the switching device in the switching structure includes the thinfilm transistor, the switching device may include a semiconductor layer210, a gate insulation layer 220, a gate electrode 231, a sourceelectrode 233, a drain electrode 235, etc.

The semiconductor layer 210 may be disposed on the buffer layer 110. Thegate insulation layer 220 may be positioned on the buffer layer 110 tocover the semiconductor layer 210. The semiconductor layer 210 mayinclude a first impurity region 211, a channel region 213, and a secondimpurity region 215. In this case, the first impurity region 211 and thesecond impurity region 215 may serve as a drain region and a sourceregion of the thin film transistor, respectively. The semiconductorlayer 210 may include a polysilicon, a polysilicon doped withimpurities, an amorphous silicon, an amorphous silicon doped withimpurities, etc. These may be used alone or in a combination thereof.The gate insulation layer 220 may include an oxide, an organicinsulation material, etc. For example, the gate insulation layer 220 mayinclude silicon oxide, hafnium oxide (HfOx), aluminum oxide (AlOx),zirconium oxide (ZrOx), titanium oxide (TiOx), tantalum oxide (TaOx), abenzocyclobutene (BCB) based resin, an acryl-based resin, etc. The gateinsulation layer 220 may have a single layer structure or a multi-layerstructure including an oxide film and/or an organic insulation materialfilm.

The gate electrode 231 may be located on the gate insulation layer 220adjacent to the semiconductor layer 210. For example, the gate electrode231 may be disposed on the gate insulation layer 220 under which thechannel region 213 of the semiconductor layer 210 may be positioned. Thegate electrode 231 may include a metal, a metal nitride, a conductivemetal oxide, a transparent conductive material, etc. For example, thegate electrode 231 may include aluminum (Al), an alloy containingaluminum, aluminum nitride (AlNx), silver (Ag), an alloy containingsilver, tungsten (W), tungsten nitride (WNx), copper (Cu), an alloycontaining copper, nickel (Ni), chromium (Cr), molybdenum (Mo), an alloycontaining molybdenum, titanium (Ti), titanium nitride (TiNx), platinum(Pt), tantalum (Ta), neodymium (Nd), scandium (Sc), tantalum nitride(TaNx), strontium ruthenium oxide (SrRuxOy), zinc oxide (ZnOx), indiumtin oxide (ITO), tin oxide (SnOx), indium oxide (InOx), gallium oxide(GaOx), indium zinc oxide (IZO), etc. The gate electrode 231 may have asingle layer structure or a multi-layer structure including a metalfilm, a metal nitride film, a conductive metal oxide film, and/or atransparent conductive material film.

In example embodiments, a gate line (not illustrated) connected to thegate electrode 231 may be disposed on the gate insulation layer 220. Agate signal may be applied to the gate electrode 231 through the gateline. The gate line may include a material substantially that is thesame as or substantially similar to that of the gate electrode 231. Forexample, the gate line may have a single layer structure or amulti-layer structure including a metal film, a metal nitride film, aconductive metal oxide film, and/or a transparent conductive materialfilm.

An insulating interlayer 240 may be disposed on the gate insulationlayer 220 to cover the gate electrode 231. The insulating interlayer 240may include an oxide, a nitride, an oxynitride, an organic insulationmaterial, etc. For example, the insulating interlayer 240 may includesilicon oxide, silicon nitride, silicon oxynitride, an acryl-basedresin, a polyimide-based resin, a siloxane-based resin, etc. These maybe used alone or in a combination thereof. The insulating interlayer 240may have a uniform thickness along a profile of the gate electrode 231.In some example embodiments, the insulating interlayer 240 may cover thegate electrode 231, and may also have a substantially level uppersurface.

The source electrode 233 and the drain electrode 235 may pass throughthe insulating interlayer 240 and the gate insulation layer 220. Thesource electrode 233 and the drain electrode 235 may make contact withthe second impurity region 215 and the first impurity region 211,respectively. Each of the source electrode 233 and the drain electrode235 may include a metal, a metal nitride, a conductive metal oxide, atransparent conductive material, etc. For example, the source and thedrain electrodes 233 and 235 may include aluminum, an alloy containingaluminum, aluminum nitride, silver, an alloy containing silver,tungsten, tungsten nitride, copper, an alloy containing copper, nickel,chromium, molybdenum, an alloy containing molybdenum, titanium, titaniumnitride, platinum, tantalum, neodymium, scandium, tantalum nitride,strontium ruthenium oxide, zinc oxide, indium tin oxide, tin oxide,indium oxide, gallium oxide, indium zinc oxide, etc. These may be usedalone or in a combination thereof. Each of the source electrode 233 andthe drain electrode 235 may have a single layer structure or amulti-layer structure including a metal film, a metal nitride film, aconductive metal oxide film, and/or a transparent conductive materialfilm.

In example embodiments, a data line (not illustrated) connected to thesource electrode 233 may be disposed on the insulating interlayer 240,and a data signal may be applied to the source electrode 233 through thedata line. The data line may include a material that is substantiallythe same as or substantially similar to that of the source electrode233. Further, the data line may have a single layer structure or amulti-layer structure including a metal film, a metal nitride film, aconductive metal oxide film, and/or a transparent conductive materialfilm. The gate line and the data line may be substantially perpendicularto each other, so that the display region of the display device may bedefined by the gate line and the data line.

An insulation layer 250 of the switching structure may be located on theinsulating interlayer 240 to cover the source electrode 233 and thedrain electrode 235. A hole may be formed through the insulation layer250 to partially expose the drain electrode 235. The insulation layer250 may include a transparent insulation material such as a transparentplastic, a transparent resin, etc. For example, the insulation layer 250may include a benzocyclobutene-based resin, an olefin-based resin, apolyimide-based resin, an acryl-based resin, a polyvinyl-based resin, asiloxane-based resin, etc. These may be used alone or in a combinationthereof. In example embodiments, the insulation layer 250 may have asubstantially flat upper surface obtained by a planarization process.For example, an upper portion of the insulation layer 250 may beplanarized by a chemical mechanical polishing (CMP) process, anetch-back process, etc. In some example embodiments, the insulationlayer 250 may include a material having a self planarizing propertywithout requiring a planarization process.

In the display device described with reference to FIG. 1, the switchingdevice including the thin film transistor may have a top gate structurein which the gate electrode 231 may be disposed on the semiconductorlayer 210, but the configuration of the switching device may not belimited thereto. For example, the switching device may have a bottomgate structure in which the gate electrode 231 may be disposed under thesemiconductor layer 210, or may include the oxide semiconductor devicehaving the active layer containing a semiconductor oxide.

Referring now to FIG. 1, the first electrode 300 may be disposed on theinsulation layer 250. In example embodiments, the first electrode 300may partially or fully fill the hole formed through the insulation layer250, and thus the first electrode 300 may make electrical contact withthe switching device. For example, the first electrode 300 may makecontact with the drain electrode 235 exposed by the hole. In someexample embodiments, a contact (not illustrated), a plug (notillustrated), or a pad (not illustrated) may be additionally disposed onthe drain electrode 235 to fill the hole of the insulation layer 250. Inthis case, the first electrode 300 may be electrically connected to thedrain electrode 235 through the pad, the plug, or the contact.

When the display device is a top emission type, the first electrode 300may serve as a reflective electrode having a suitable reflectivity. Inthis case, the second electrode 500 may serve as a transparent electrodehaving a suitable transmittance or a transflective electrode that issemi-transparent. Materials in the first and the second electrodes 300and 500 may vary in accordance with an emission type of the displaydevice. For example, the first electrode 300 may serve as a transparentelectrode or a transflective electrode, whereas the second electrode 500may serve as a reflective electrode in case that the display device is abottom emission type. Here, the term “reflective” may indicate an objecthaving a reflectivity of about 70% to about 100% relative to an incidentlight, and the term “transflective” may indicate an object having areflectivity of about 30% to about 70% with respect to an incidentlight. Further, the term “transparent” may indicate an object having areflectivity of about 0% to about 30% with respect to an incident light.

In example embodiments, when the first electrode 300 serves as thereflective electrode, the first electrode 300 may include a metal and/oran alloy having a relatively high reflectivity. For example, the firstelectrode 300 may include silver (Ag), aluminum (Al), platinum (Pt),gold (Au), chrome (Cr), tungsten (W), molybdenum (Mo), titanium (Ti),palladium (Pa), an alloy thereof, etc. These may be used alone or in acombination thereof. Examples of the alloy in the first electrode 300may include an ACA (Ag—Cu—Au) alloy, an APC (Ag—Pd—Cu) alloy, etc. Inexample embodiments, the first electrode 300 may have a single layerstructure or a multi-layer structure including a metal film and/or analloy film.

When the second electrode 500 serves as the transflective electrode, thesecond electrode 500 may include a single metal film. In this case, thesecond electrode 500 may have a set or predetermined reflectivity and aset or predetermined transmittance. When the second electrode 500 has arelatively large thickness, the display device may have relatively lowluminance efficiency, so that the second electrode 500 should have arelatively thin thickness. For example, the second electrode 500 mayhave a thickness below about 30 nm. The second electrode 500 may includea metal and/or an alloy such as silver (Ag), aluminum (Al), platinum(Pt), gold (Au), chrome (Cr), tungsten (W), molybdenum (Mo), titanium(Ti), palladium (Pa), alloys of these metals, etc. These may be usedalone or in a combination thereof.

In some example embodiments, the second electrode 500 may include atransparent conductive material, and thus the second electrode may serveas the transparent electrode. For example, the second electrode 500 mayinclude an indium zinc oxide, an indium tin oxide, a gallium-tin oxide,a zinc oxide, a gallium oxide, a tin oxide, an indium oxide, etc. Thesemay be used alone or in a combination thereof. The second electrode 500may have a multi-layer structure including a plurality of thetransparent films or a plurality of the transflective films havingdifferent reflective indices.

In example embodiments, the first electrode 300 may serve as an anodefor providing holes into a first hole injection layer 410 of the lightemitting structure 400. Here, the second electrode 500 may serve as acathode for supplying electrons into an electron transfer layer 490.However, functions of the first and the second electrodes 300 and 500may not be limited thereto, and roles of the first electrode 300 and thesecond electrode 500 may be modified in accordance with the emissiontype of the display device. A stacked construction (or configuration)having a hole transfer layer, an organic light emitting layer, and anelectron transfer layer in the light emitting structure 400 may vary inaccordance with the functions of the first electrode 300 and the secondelectrode 500.

In example embodiments, the display region of the display device mayhave the first sub-pixel region (I), the second sub-pixel region (II),and the third sub-pixel region (III) as illustrated in FIG. 1.

An optical distance controlling insulation layer 350 may be disposed onthe first electrode 300 in the display region, and a protection layer280 may be located on the insulation layer 250 in the non-display regionadjacent to the display region. In example embodiments, the protectionlayer 280 may extend to partially cover the first electrode 300 that iselectrically connected to the drain electrode 235. The protection layer280 may include an oxide, a nitride, an oxynitride, an organicinsulation material, etc. For example, the protection layer may includesilicon oxide, silicon nitride, silicon oxy nitride, abenzocyclobutene-based resin, an olefin-based resin, a polyimide-basedresin, an acryl-based resin, a polyvinyl-based resin, a siloxane-basedresin, etc. These may be used alone or in a combination thereof. In someexample embodiments, the display device may not include the protectionlayer 280, and thus the display device may have a simpler construction.

In example embodiments, the optical distance controlling insulationlayer 350 may be positioned on the first electrode 300 in the firstsub-pixel region (I) and the second sub-pixel region (II). In someexample embodiments, the optical distance controlling insulation layer350 may be located on the first electrode 300 in the first sub-pixelregion (I), the second sub-pixel region (II), and the third sub-pixelregion (III). In other example embodiments, the optical distancecontrolling insulation layer 350 may be disposed on the first electrode300 located in at least one of the first sub-pixel region (I), thesecond sub-pixel region (II), or the third sub-pixel region (III).

The optical distance controlling insulation layer 350 may adjust or mayensure an optical resonance distance for generating optical resonancesof light emitted from the light emitting structure 400. In exampleembodiments, the optical distance controlling insulation layer 350 mayhave various thicknesses substantially different in the first, thesecond, and the third sub-pixel regions (I, II, and III). For example, afirst portion of the optical distance controlling insulation layer 350in the first sub-pixel region (I) may have a thickness that issubstantially larger than that of a second portion of the opticaldistance controlling insulation layer 350 in the second sub-pixel region(II). Distances between the first electrode 300 and the second electrode500 in the first, the second, and the third sub-pixel regions (I, II,and III) may vary depending on the thickness difference of the opticaldistance controlling insulation layer 350 in the first, the second, andthe third sub-pixel regions (I, II, and III).

The optical distance controlling insulation layer 350 may besubstantially transparent. For example, the optical distance controllinginsulation layer 350 may have a transmittance of about 70% to about 100%relative to an incident light. In example embodiments, the opticaldistance controlling insulation layer 350 may include a material that issubstantially the same as or substantially similar to that of the firsthole injection layer 410. In some example embodiments, the opticaldistance controlling insulation layer 350 may include a transparentinsulation material. For example, the optical distance controllinginsulation layer 350 may include a benzocyclobutene-based resin, anolefin-based resin, a polyimide-based resin, an acryl-based resin, apolyvinyl-based resin, a siloxane-based resin, etc. These may be usedalone or in a combination thereof.

Generally, the term “optical resonance” or “microcavity effect”indicates the increase of luminance and/or intensity of light having aset or predetermined wavelength when an optical distance between tworeflective or transflective faces satisfies the conditions ofconstructive interference of the light having the set or predeterminedwavelength. The term “reflective” may indicate a reflectivity of about70% to about 100% relative to an incident light, and the term“transflective” may indicate a reflectivity of about 30% to about 70%with respect to an incident light. Here, the optical distance may besubstantially equal to a value obtained by multiplying the refractionindex (n) of a layer and/or an electrode with the thickness (d) of thelayer or the electrode when a light passes through a layer or anelectrode. In the case that the light passes through a plurality oflayers or electrodes having different refraction indices, the wholeoptical distance of the plurality of layers or electrodes may besubstantially equal to the sum (Σn·d) of respective optical distance(n·d) of each layer or electrode.

When a plurality of layers or electrodes are disposed between the tworeflective or transflective faces, the optical resonance of lightbetween the two reflective or transflective faces may be represented bythe following equation (1):

$\begin{matrix}{{2\; \pi \; m} = {\sum\limits_{j}\left( {\frac{2\; \pi \; 2\; n_{j}d_{j}}{\lambda} + \theta_{j}} \right)}} & (1)\end{matrix}$

In the above equation (1), n_(j) denotes an index of refraction of aj^(th) layer or electrode among the plurality of layers or electrodesinterposed between two reflective or transflective faces when a lighthaving a set or predetermined wavelength (λ) passes through the j^(th)layer or electrode. Additionally, d_(j) indicates a thickness of thej^(th) layer or electrode and m represents an arbitrary integer.Furthermore, θ_(j) represents a phase change of the light when the lightpasses the j^(th) layer or electrode or the light is reflected from thereflective or transflective face. In the case that the above equation(1) is modified relative to an optical distance, the following equation(2) may be obtained from the above equation (1):

$\begin{matrix}\begin{matrix}{L = {\sum\limits_{j}{n_{j}d_{j}}}} \\{= {\frac{\lambda}{2}\left( {m - {\sum\frac{\theta_{j}}{2\; \pi}}} \right)}} \\{= {\frac{\lambda}{2}\left( {m - \frac{(I)}{2\; \pi}} \right)}}\end{matrix} & (2)\end{matrix}$

As for the above equation (2), L represents an optical distance forgenerating the optical resonance of the light having the set orpredetermined wavelength (λ). Hereinafter, the optical distance suitablefor the optical resonance of the light having the set or predeterminedwavelength may be referred to as “an optical resonance distance (L).”Further, φ indicates the sum of phase changes of the light generatedwithin the optical resonance distance (L). The sum of phase changes φmay be in a range of −π radian to π radian. The term “peak wavelength”refers to a wavelength of light that generates an optical resonancewithin a specific optical resonance distance (L).

According to the above equation (2), the optical resonance distance (L)for producing the optical resonance of the light having the set orpredetermined wavelength (λ) may vary in accordance with the integer(m). In the case that the optical resonance distance (L) is relativelylarge, different integers (m) (i.e., the values of the above equation(2)) respectively corresponding to different peak wavelengths may beobtained within one optical resonance distance (L).

For simplicity, the sum of the phase changes of the light generatedwithin the optical resonance distance (L) is assumed to be zero, a peakwavelength of red light is assumed to be about 660 nm, and a peakwavelength of blue light is assumed to be about 440 nm. The opticalresonance distance (L) that generates the optical resonance for redlight may have several values of about 330 nm (m=1), about 660 nm (m=2),about 990 nm (m=3), about 1,320 nm (m=4), etc. The optical resonancedistance (L) that generates the optical resonance for blue light mayhave several values of about 220 nm (m=1), about 440 nm (m=2), about 660nm (m=3), about 880 nm (m=4), etc. That is, a plurality of opticalresonance distances (L) may be obtained relative to one peak wavelength.However, the optical resonance distance may be limited by the size ofthe display device.

Referring now to FIG. 1, the first sub-pixel region (I) of the displaydevice may be a region for mainly emitting red light, the secondsub-pixel region (II) of the display device may be a region for mainlyemitting green light, and the third sub-pixel region (III) of thedisplay device may be a region for mainly emitting blue light.Therefore, a first optical resonance distance in the first sub-pixelregion (I) may be adjusted to generate the optical resonance for redlight, a second optical resonance distance in the second sub-pixelregion (II) may be adjusted to generate the optical resonance for greenlight, and a third optical resonance distance in the third sub-pixelregion (III) may be adjusted to generate the optical resonance for bluelight.

In example embodiments, the first, the second, and the third opticalresonance distances may be adjusted by controlling the thicknesses ofthe optical distance controlling insulation layer 350 and/or arefraction index of the optical distance controlling insulation layer350. In the case that a thickness of the light emitting structure 400 inthe first, the second, and the third sub-pixel regions (I, II, and III)is constant, the first, the second, and the third optical resonancedistances may be adjusted by controlling the thickness and/or therefraction index of the optical distance controlling insulation layer350.

As for the above equation (2), when m is constant, the optical resonancedistance may increase in proportion to the peak wavelength. Therefore,the first optical resonance distance in the first sub-pixel region (I)for emitting red light may be substantially larger than the secondoptical resonance distance in the second sub-pixel region (II) foremitting green light. Further, the second optical resonance distance inthe second sub-pixel region (II) may be substantially larger than thethird optical resonance distance in the third sub-pixel region (III) foremitting blue light. Therefore, the optical distance controllinginsulation layer 350 in the first sub-pixel region (I) may have athickness substantially larger than that in the second sub-pixel region(II) or the third sub-pixel region (III).

In the display device in accordance with example embodiments, the firstto the third sub-pixel regions (I, II, and Ill) may have substantiallydifferent optical resonance distances, so that different colors of lighthaving different wavelengths may be emitted from the first to the thirdsub-pixel regions (I, II, and III), respectively. Therefore, the displaydevice may have improved purity of colors of light, enhanced brightness,and increased color gamut of light, and the display device may havereduced driving voltage to extend a lifetime of the display device.

As illustrated in FIG. 1, the light emitting structure 400 including theoptical distance controlling insulation layer 350 may be disposed on thefirst electrode 300. In example embodiments, the light emittingstructure 400 may include the first hole injection layer 410, a holetransfer layer 420, a first organic light emitting layer 430, a blockingmember 440, a charge generation layer 450, a second hole injection layer460, a second organic light emitting layer 480, the electron transferlayer 490, etc.

In example embodiments, the first hole injection layer 410 may bedisposed on the first electrode 300 to cover the optical distancecontrolling insulation layer 350. The first hole injection layer 410 maypromote a hole injection from the first electrode 300 into the firstorganic light emitting layer 430. For example, the first hole injectionlayer 410 may include CuPc (cupper phthalocyanine), PEDOT(poly(3,4)-ethylenedioxythiophene), PANI (polyaniline), NPD(N,N-dinaphthyl-N,N′-diphenyl benzidine), etc. However, a material inthe first hole injection layer 410 may not be limited thereto.

The hole transfer layer 420 may be located on the first hole injectionlayer 410. The hole transfer layer 420 may improve a movement of holesfrom the first hole injection layer 410. Here, when the highest occupiedmolecular energy (HOMO) of the hole transfer layer 420 is substantiallylower than a work function of the first electrode 300, and issubstantially higher than the highest occupied molecular energy (HOMO)of the first organic light emitting layer 430, an efficiency of themovement of holes may be optimized or improved. For example, the holetransfer layer 420 may include NPD(N,N-dinaphthyl-N,N′-diphenylbenzidine), TPD(N,N′-bis-(3-methylphenyl)-N,N′-bis-(phenyl)-benzidine), s-TAD, MTDATA(4,4′,4″-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine), etc.However, a material in the hole transfer layer 420 may not be limitedthereto.

The first organic light emitting layer 430 may be disposed on the holetransfer layer 420. The first organic light emitting layer 430 mayinclude a blue fluorescent dopant or a blue phosphorescent dopantdispersed in a host. In example embodiments, the first organic lightemitting layer 430 may substantially emit blue light, and thus colorstability thereof may be improved, and a life time of the first organiclight emitting layer 430 may be extended.

The charge generation layer 450 may be disposed on the first organiclight emitting layer 430. The charge generation layer 450 may serve asan anode for the first organic light emitting layer 430 and also mayserve as a cathode for the second organic light emitting layer 480.

The charge generation layer 450 may have a single layer structure or amulti-layer structure. In example embodiments, the charge generationlayer 450 may have the single layer structure including a metal oxidefilm containing a vanadium oxide (VOx), a tungsten oxide (WOx), etc. Insome example embodiments, the charge generation layer 450 may have adouble layer structure including a metal oxide film and a metal film. Inthis case, the metal oxide film may include a vanadium oxide (VOx), atungsten oxide (WOx), etc. Further, the metal film may include aluminum,silver, etc.

When a voltage is applied to the first electrode 300 and/or the secondelectrode 500, charges (e.g., electrons or holes) may be generated inthe charge generation layer 450, and the generated charges (electrons orholes) may be supplied from the charge generation layer 450 to theadjacent first organic light emitting layer 430 and/or the adjacentsecond organic light emitting layer 480. Therefore, distribution of thecharges may be substantially uniform in the first, the second, and thethird sub-pixel regions (I, II and III), so that the red, the green, andthe blue lights may be substantially uniformly emitted. Further, thedisplay device including a plurality of organic light emitting layersmay have enhanced luminance efficiency that is larger than that of adisplay device including a single organic light emitting layer.

In some example embodiments, in order to reduce the driving voltage andto increase the luminance efficiency, an additional electron transferlayer (not illustrated) and/or an electron injection layer (notillustrated) may be disposed between the first organic light emittinglayer 430 and the charge generation layer 450.

The second hole injection layer 460 may be positioned on the chargegeneration layer 450. The second hole injection layer 460 may besubstantially the same as or substantially similar to the first holeinjection layer 410 in the aspects of the role and the material.

The second organic light emitting layer 480 may be disposed on thesecond hole injection layer 460. The second organic light emitting layer480 may have a single layer structure or a multi-layer structure. Inexample embodiments, the second organic light emitting layer 480 mayhave a double layer structure including a green light-emitting film anda red light-emitting film. The green light-emitting film may include agreen dopant dispersed in a host, and the red light-emitting film mayinclude a red dopant dispersed in a host. In some example embodiments,the second organic light emitting layer 480 may have the single layerstructure including a green dopant and a red dopant dispersed in a host.

The electron transfer layer 490 may be disposed on the second organiclight emitting layer 480. The electron transfer layer 490 may enhance amovement of electrons to the second organic light emitting layer 480.For example, the electron transfer layer 490 may include(tris(8-hydroxyquinolino)aluminum), PBD, TAZ, spiro-PBD, BAlq, SAlq,etc. However, a material in the electron transfer layer 490 may not belimited thereto.

In some example embodiments, in order to reduce the driving voltage andto increase the luminance efficiency, an additional hole transfer layer(not illustrated) may be located between the second hole injection layer460 and the second organic light emitting layer 480. Further, anadditional electron injection layer (not illustrated) may be disposedbetween the electron transfer layer 490 and the second electrode 500.

As illustrated in FIG. 1, the blocking member 440 may be disposed on thefirst organic light emitting layer 430 in the first sub-pixel region(I). In example embodiments, the blocking member 440 may prevent orreduce a movement of electrons. In this case, the blocking member 440may include fullerene, a polymer including substituted triarylamine, acarbazole based polymer,

-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)cyclohexane (TAPC),-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)cyclopentane,-   4,4′-(9H-fluoren-9-ylidene)bis[N,N-bis(4-methylphenyl)-benzenamine,-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-4-phenylcyclohexane,-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-4-methylcyclohexane,-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-3-phenylpropane,-   Bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylpenyl)methane,-   Bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)ethane,-   4-(4-Diethylaminophenyl)triphenylmethane,-   4,4′-Bis(4-diethylaminophenyl)diphenylmethane,-   N,N-bis[2,5-dimethyl-4-[(3-methylphenyl)phenylamino]phenyl]-2,5-dimethyl-N′-(3-methy    (phenyl)-N′-phenyl-1,4-benzenediamine,-   4-(9H-carbazol-9-yl)-N,N-bis[4-(9H-carbazol-9-yl)phenyl]-benzenamine    (TCTA),-   4-(3-phenyl-9H-carbazol-9-yl)-N,N-bis[4(3-phenyl-9H-carbazol-9-yl)phenyl]-benzenamine,9,9′-(2,2′-dimethyl[1,1′-biphenyl]-4,4′-diyl)bis-9H-carbazole    (CDBP),-   9,9′-[1,1′-biphenyl]-4,4′-diyl)bis-9H-carbazole (CBP),-   9,9′-(1,3-phenylene)bis-9H-carbazole (mCP),    9,9′-(1,4-phenylene)bis-9H-carbazole,-   9,9′,9″-(1,3,5-benzenetriyl)tris-9H-carbazole,-   9,9′-(1,4-phenylene)bis[N,N,N′,N′-tetraphenyl-9H-carbazole-3,6-diamine,-   9-[4-(9H-carbazol-9-yl)phenyl]-N,N-diphenyl-9H-carbazol-3-amine,-   9,9′-(1,4-phenylene)bis[N,N-diphenyl-9H-carbazol-3-amine,-   9-[4-(9H-carbazol-9-yl)phenyl]-N,N,N′,N′-tetraphenyl-9H-carbazole-3,6-diamine,    9-phenyl-9H-carbazol, etc. Further, the blocking member 440 may have    a thickness of about 30 nm or more to effectively prevent or reduce    the movement of electrons. For example, the blocking member 440 may    have a thickness between about 30 nm and about 150 nm. In some    example embodiments, the blocking member 440 may include a material    having a relatively large highest occupied molecular energy (HOMO)    and may be transparent.

In example embodiments, the blocking member 440 may prevent or reducethe movement of electrons from the charge generation layer 450 to thefirst organic light emitting layer 430 in the first sub-pixel region(I). Therefore, the electrons may not be supplied to the first organiclight emitting layer 430 in the first sub-pixel region (I) because ofthe blocking member 440, so that the first organic light emitting layer430 in the first sub-pixel region (I) may not substantially emit light.

In the display device described with reference to FIG. 1, the opticaldistance controlling insulation layer 350 may have substantiallydifferent thicknesses in the first sub-pixel region (I) and the secondsub-pixel region (II). However the optical distance controllinginsulation layer 350 may not be limited thereto. For example, theoptical distance controlling insulation layer 350 may have asubstantially uniform thickness in the first sub-pixel region (I) andthe second sub-pixel region (II). In this case, the first and the secondoptical resonance distances of the first and the second sub-pixelregions (I and II) may be adjusted by controlling a thickness of theblocking member 440.

FIG. 2 is a graph showing peak wavelengths of optical resonances of redlight and blue light depending on a thickness of an electron blockinglayer.

Referring to FIG. 2, as for a display device (IV) which does not includea blocking member such as an electron blocking layer, when an opticalresonance distance is adjusted to generate an optical resonance for redlight, an optical resonance for blue light occurs concurrently (e.g.,simultaneously). As described above, the optical resonance distance forgenerating the optical resonance for the red light (m=2) may have avalue of about 660 nm that is substantially similar to that for bluelight (m=3), so that the optical resonances for red light and blue lightare generated concurrently (e.g., simultaneously) in the display device(IV), thereby reducing purity of colors of light of the display device(IV). As for a display device (V) including an electron blocking layerhaving a thickness of about 30 nm, a display device (VI) including anelectron blocking layer having a thickness of about 50 nm, and a displaydevice (VII) including an electron blocking layer having a thickness ofabout 100 nm, an optical resonance for red light is generated withoutcausing an optical resonance for blue light. Therefore, purity of colorsof light in the display device may be improved by applying the blockingmember such as the electron blocking layer.

Referring to FIGS. 1 and 2, when the blocking member 440 is disposedbetween the first organic light emitting layer 430 and the chargegeneration layer 450 in the first sub-pixel region (I), the blockingmember 440 may block the movement of electrons from the chargegeneration layer 450 to the first organic light emitting layer 430. Thatis, excitons may not be generated in the first organic light emittinglayer 430 in the first sub-pixel region (I) because of the blockingmember 440, so that emission of blue light may be prevented or reducedby the blocking member 440. Therefore, substantially only red light maybe emitted by the optical resonance in the first sub-pixel region (I),light having a high color purity may be emitted in the first, thesecond, and the third sub-pixel regions (I, II, and III), and thedisplay device may ensure high purity of light colors and highbrightness without a color filter. As a result, a constitution of thedisplay device may be simplified, manufacturing costs thereof may bereduced, and manufacturing processes may be simplified. Further, a colorfilter is not used over the organic light emitting layers, so that areduction in the brightness caused by the color filter may be prevented.

FIG. 3 is a cross-sectional view illustrating a display device having alight emitting structure in accordance with some example embodiments.The display device illustrated in FIG. 3 may have a constructionsubstantially the same as or substantially similar to that of thedisplay device described with reference to FIG. 1, except for a lightemitting structure.

Referring to FIG. 3, the display device may include a substrate 100, aswitching structure, a first electrode 300, a light emitting structure402, a second electrode 500, etc. A display region of the display devicemay be divided into first, second, and third sub-pixel regions (I, II,and III), and thus the light emitting structure 402 may be divided intothe first, the second, and the third sub-pixel regions (I, II, and III).

The switching structure including a switching device and at least one ormore insulation layers may be disposed on the substrate 100 having abuffer layer 110. The switching structure may include a semiconductorlayer 210, a gate insulation layer 220, a gate electrode 231, aninsulating interlayer 240, a source electrode 233, a drain electrode235, an insulation layer 250, etc. In this case, the semiconductor layer210 may include a first impurity region 211, a channel region 213, and asecond impurity region 215. A construction of the switching structuremay be substantially the same as or substantially similar to that of theswitching structure described with reference to FIG. 1.

The first electrode 300 may be disposed on the insulation layer 250 inthe display region, and a protection layer 280 may be disposed on theinsulation layer 250 in a non-display region adjacent to the displayregion. The second electrode 500 may be located above the firstelectrode 300, and the first and second electrodes 300 and 500 are onopposite sides of the light emitting structure 402. An optical distancecontrolling insulation layer 350 and the light emitting structure 402may be disposed between the first electrode 300 and the second electrode500.

The optical distance controlling insulation layer 350 may be disposed onthe first electrode 300 in the display region. In example embodiments,the optical distance controlling insulation layer 350 may be disposedonly in the first sub-pixel region (I) and the second sub-pixel region(II). In some example embodiments, the optical distance controllinginsulation layer 350 may be positioned in the first sub-pixel region(I), the second sub-pixel region (II), and the third sub-pixel region(III). The optical distance controlling insulation layer 350 may havesubstantially different thicknesses in the first, the second, and thethird sub-pixel regions (I, II, and III), and thus gaps (or distances)between the first electrode 300 and the second electrode 500 may besubstantially different in the first, the second, and the thirdsub-pixel regions (I, II, and III), thereby generating opticalresonances for different wavelengths of lights with different colors.

A first hole injection layer 410 of the light emitting structure 402 maybe disposed on the first electrode 300 to cover the optical distancecontrolling insulation layer 350. The first hole injection layer 410 mayimprove a hole injection from the first electrode 300 to a first organiclight emitting layer 430. The first organic light emitting layer 430 maybe disposed on the first hole injection layer 410. The first organiclight emitting layer 430 may have a single layer structure or a doublelayer structure. In example embodiments, the second organic lightemitting layer 480 may have the double layer structure including a greenlight emitting film and a red light emitting film. The green lightemitting film may include a green dopant dispersed in a host, and thered light emitting layer may include a red dopant dispersed in a host.In some example embodiments, the second organic light emitting layer 480may have the single layer structure including a green dopant and a reddopant dispersed in a host.

A charge generation layer 450 may be disposed on the first organic lightemitting layer 430. The charge generation layer 450 may serve as ananode for the first organic light emitting layer 430, and may serve as acathode for a second organic light emitting layer 480. The chargegeneration layer 450 may have a single layer structure or a multi-layerstructure. A second hole injection layer 460 and a hole transfer layer470 may be located on the charge generation layer 450 to enhance amovement of holes from the charge generation layer 450 to the secondorganic light emitting layer 480.

The second organic light emitting layer 480 may be disposed on the holetransfer layer 470. For example, the second organic light emitting layer480 may include a blue light emitting film including a blue dopantdispersed in a host. An electron transfer layer 490 may be disposed onthe second organic light emitting layer 480 to improve a movement ofelectrons.

In example embodiments, a blocking member 440 may include an electronblocking layer. In this case, the electron blocking layer may bedisposed between the second organic light emitting layer 480 and theelectron transfer layer 490 in the first sub-pixel region (I). Theblocking member 440 including the electron blocking layer may prevent orreduce the movement of electrons from the electron transfer layer 490 tothe second organic light emitting layer 480. Therefore, electrons maynot be supplied to the second organic light emitting layer 480 in thefirst sub-pixel region (I) because of the blocking member 440, so thatthe second organic light emitting layer 480 in the first sub-pixelregion (I) may not emit light.

In comparison with the display device described with FIG. 1, the displaydevice with reference to FIG. 3 may include the light emitting structure402 where the blue light emitting film may change positions with the redand the green light emitting films, and positions of the blocking member440 and the hole transfer layer 470 may also change. Even though theremay be a position change, each optical resonances may be generated inthe first, the second, and the third sub-pixel regions (I, II, and III),and emission of blue light may be prevented or reduced by the blockingmember 440 in the first sub-pixel region (I), so that the display devicemay ensure high purity of colors of light, improved color gamut oflight, and high brightness without a color filter.

FIG. 4 is a cross-sectional view illustrating a display device having alight emitting structure in accordance with some example embodiments.The display device illustrated in FIG. 4 may have a constructionsubstantially the same as or substantially similar to that of thedisplay device described with reference to FIG. 1, except for a lightemitting structure.

Referring to FIG. 4, the display device may include a substrate 100, aswitching structure, a first electrode 300, a light emitting structure404, a second electrode 500, etc. The display device may include anon-display region and a display region divided into first, second, andthird sub-pixel regions (I, II, and III), and thus the light emittingstructure 404 in the display region may be divided into the first, thesecond, and the third sub-pixel regions (I, II, and III).

A buffer layer 110 may be disposed on the substrate 100, and theswitching structure may be disposed on the buffer layer 110. Theswitching structure may include a semiconductor layer 210 (including afirst impurity region 211, a channel region 213, and a second impurityregion 215), a gate insulation layer 220, a gate electrode 231, aninsulating interlayer 240, a source electrode 233, a drain electrode235, an insulation layer 250, etc. A construction of the switchingstructure has been described in detail with reference to FIG. 1, so thatany further descriptions will be omitted.

In example embodiments, an optical distance controlling insulation layer350 may be disposed on the first electrode 300. In example embodiments,the optical distance controlling insulation layer 350 may be positionedonly in the first sub-pixel region (I) and the second sub-pixel region(II). In some example embodiments, the optical distance controllinginsulation layer 350 may be disposed in the first sub-pixel region (I),the second sub-pixel region (II), and the third sub-pixel region (III).The optical distance controlling insulation layer 350 may havesubstantially different thicknesses in the first, the second, and thethird sub-pixel regions (I, II, and III), and thus gaps between thefirst electrode 300 and the second electrode 500 may be substantiallydifferent in the first, the second, and the third sub-pixel regions (I,II, and III), thereby generating the optical resonances for differentwavelengths of color lights.

The light emitting structure 404 in the display region may include afirst hole injection layer 410, a hole transfer layer 420, a firstorganic light emitting layer 430, an additional electron transfer layer435, a blocking member 440, a charge generation layer 450, a second holeinjection layer 460, a second organic light emitting layer 480, anelectron transfer layer 490, etc. The light emitting structure 404 mayhave a constitution substantially the same as or substantially similarto that of the light emitting structure 400 described with reference toFIG. 1.

In example embodiments, the additional electron transfer layer 435 maybe disposed between the first organic light emitting layer 430 and thecharge generation layer 450. The additional electron transfer layer 435may enhance a movement of electrons from the charge generation layer 450to the first organic light emitting layer 430, and thus luminanceefficiency of the light emitting structure 404 may be improved. Theblocking member 440 may include an electron blocking layer. In thiscase, the electron blocking layer may be disposed on the additionalelectron transfer layer 435 in the first sub-pixel region (I). Theblocking member 440 may block the movement of electrons from the chargegeneration layer 450 to the first organic light emitting layer 430 inthe first sub-pixel region (I). Therefore, the electrons may not besupplied to the first organic light emitting layer 430 in the firstsub-pixel region (I) because of the blocking member 440, so that thefirst organic light emitting layer 430 in the first sub-pixel region (I)may not emit light. In some example embodiments, a hole blocking layer(not illustrated) instead of the additional electron transfer layer 435may be disposed between the first organic light emitting layer 430 andthe charge generation layer 450. The hole blocking layer may block amovement of holes from the first organic light emitting layer 430 to thecharge generation layer 450, thereby improving the luminance efficiencyof the light emitting structure 404.

In comparison with the display device described with FIG. 1, the displaydevice with reference to FIG. 4 includes the light emitting structure404 where the blocking member 440 may be separated from the firstorganic light emitting layer 430 including the blue light-emitting film.Even though there may be a position change, a movement of electrons tothe blue light-emitting film may be blocked or reduced by the blockingmember 440, so that substantially only red light may be emitted in thefirst sub-pixel region (I). Therefore, the display device may ensurehigh purity of colors of light, improved color gamut of light, and highbrightness without a color filter.

FIG. 5 is a cross-sectional view illustrating a display device having alight emitting structure in accordance with some example embodiments.The display device illustrated in FIG. 5 may have a constructionsubstantially the same as or substantially similar to that of thedisplay device described with reference to FIG. 1, except for a lightemitting structure.

Referring to FIG. 5, the display device may include a substrate 100, aswitching structure, a first electrode 300, a light emitting structure406, a second electrode 500, etc. The display device and the lightemitting structure 406 may include first, second, and third sub-pixelregions (I, II, and III).

The switching structure may include one or more insulation layers and aswitching device. For example, the switching structure may include asemiconductor layer 210 (having a channel region 213, a first impurityregion 211, and a second impurity region 215), a gate insulation layer220, a gate electrode 231, a source electrode 233, a drain electrode235, etc. Further, the one or more insulation layers may include aninsulating interlayer 240, an insulation layer 250, etc.

In example embodiments, an optical distance controlling insulation layer350 may be disposed on the first electrode 300 in a display region ofthe display device. The optical distance controlling insulation layer350 may be disposed in the first sub-pixel region (I), the secondsub-pixel region (II), and/or the third sub-pixel region (III). In thiscase, the optical distance controlling insulation layer 350 may havesubstantially different thicknesses in the first, the second, and thethird sub-pixel regions (I, II, and III). Therefore, first, second, andthird optical resonance distances may be provided between the firstelectrode 300 and the second electrode 500 in the first, the second, andthe third sub-pixel regions (I, II, and III), respectively.

In example embodiments, the light emitting structure 406 may include afirst hole injection layer 410, a hole transfer layer 420, a blockingmember 425, a first organic light emitting layer 430, a chargegeneration layer 450, a second hole injection layer 460, a secondorganic light emitting layer 480, an electron transfer layer 490, etc.The blocking member 425 including an exciton quenching layer (EQL) maybe disposed between the first organic light emitting layer 430 and thehole transfer layer 420 in the first sub-pixel region of the lightemitting structure 406. In this case, the exciton quenching layer of theblocking member 425 may include fullerene, a polymer includingsubstituted triarylamine, a carbazole based polymer,

-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)cyclohexane (TAPC),-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)cyclopentane,-   4,4′-(9H-fluoren-9-ylidene)bis[N,N-bis(4-methylphenyl)-benzenamine,-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-4-phenylcyclohexane,-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-4-methylcyclohexane,-   1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-3-phenylpropane,-   Bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylpenyl)methane,-   Bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)ethane,-   4-(4-Diethylaminophenyl)triphenylmethane,-   4,4′-Bis(4-diethylaminophenyl)diphenylmethane,-   N,N-bis[2,5-dimethyl-4-[(3-methylphenyl)phenylamino]phenyl]-2,5-dimethyl-N′-(3-methylphenyl)-N′-phenyl-1,4-benzenediamine,-   4-(9H-carbazol-9-yl)-N,N-bis[4-(9H-carbazol-9-yl)phenyl]-benzenamine    (TCTA),-   4-(3-phenyl-9H-carbazol-9-yl)-N,N-bis[4(3-phenyl-9H-carbazol-9-yl)phenyl]-benzenamine,9,9′-(2,2′-dimethyl[1,1′-biphenyl]-4,4′-diyl)bis-9H-carbazole    (CDBP),-   9,9′-[1,1′-biphenyl]-4,4′-diyl)bis-9H-carbazole (CBP),-   9,9′-(1,3-phenylene)bis-9H-carbazole (mCP),    9,9′-(1,4-phenylene)bis-9H-carbazole,-   9,9′,9″-(1,3,5-benzenetriyl)tris-9H-carbazole,-   9,9′-(1,4-phenylene)bis[N,N,N′,N′-tetraphenyl-9H-carbazole-3,6-diamine,-   9-[4-(9H-carbazol-9-yl)phenyl]-N,N-diphenyl-9H-carbazol-3-amine,-   9,9′-(1,4-phenylene)bis[N,N-diphenyl-9H-carbazol-3-amine,-   9-[4-(9H-carbazol-9-yl)phenyl]-N,N,N′,N′-tetraphenyl-9H-carbazole-3,6-diamine,9-phenyl-9H-carbazol,    etc. When operating the display device, electrons and holes may    collide with each other between the first organic light emitting    layer 430 and the hole transfer layer 420 to generate excitons. The    blocking member 425 including the exciton quenching layer may    transform high energy electrons or excitons near the exciton    quenching layer to low energy electrons or excitons. Therefore, the    electrons or the excitons which may participate in the light    emitting process may not exist, so that the first organic light    emitting layer 430 may not emit light.

In comparison with the display device described with FIG. 1, the displaydevice with reference to FIG. 5 may include the blocking member 425having the exciton quenching layer instead of an electron blocking layerin the first sub-pixel region. Even though there may be a positionchange, substantially only red light may be emitted in the firstsub-pixel region (I), and emission of blue light may be prevented orreduced.

FIG. 6 is a cross-sectional view illustrating a display device having alight emitting structure in accordance with some example embodiments.The display device illustrated in FIG. 6 may have a constructionsubstantially the same as or substantially similar to that of thedisplay device described with reference to FIG. 1 except for a firstelectrode 300, a second electrode 500, and an emission type.

Referring to FIG. 6, the display device may include a substrate 100, aswitching structure, the first electrode 300, a light emitting structure408, the second electrode 500, etc.

The switching structure may be disposed on the substrate 100 having abuffer layer 110. The switching structure may include a switching deviceand one or more insulation layers. The switching device may include asemiconductor layer 210, a gate insulation layer 220, a gate electrode231, a source electrode 233, a drain electrode 235, etc. The one or moreinsulation layers may include an insulating interlayer 240, aninsulation layer 250, etc.

In example embodiments, when the display device is a bottom emissiontype, the first electrode 300 may serve as a transflective electrodehaving a reflectivity of about 30% to about 70% with respect to anincident light, and the second electrode 500 may serve as a reflectiveelectrode having a reflectivity of about 70% to about 100% relative toan incident light.

When the first electrode 300 is a transflective electrode, the firstelectrode 300 may include a metal, an alloy, a conductive metal oxide, atransparent inorganic material doped with impurities, etc. For example,the first electrode 300 may have a multi-layer structure including aplurality of the transparent films or a plurality of the transflectivefilms having different reflective indices. In example embodiments, thefirst electrode 300 may have a triple layer structure including a firstelectrode film, a second electrode film, and a third electrode film. Inthis case, the first electrode film and the third electrode film mayinclude a metal oxide containing an indium tin oxide, an indium zincoxide, a zinc oxide, etc. The second electrode film may include amagnesium-silver alloy, silver, a silver-palladium-copper alloy, etc.Even though the second electrode film may include a metal having arelatively high reflectivity, the second electrode film may have arelatively thin thickness, thereby serving as a transflective electrode.

When the second electrode 500 is the reflective electrode, the secondelectrode 500 may include aluminum, platinum, silver, gold, chromium,tungsten, molybdenum, titanium, palladium, and alloys of these metals(e.g., Ag—Cu—Au (ACA) alloy or Ag—Pd—Cu (APC) alloy), etc. Thesematerials may be used alone or in a combination thereof. When the secondelectrode 500 is the reflective electrode, a light generated in thelight emitting structure 408 may pass through the first electrode 300and the substrate 100, such that the display device is a bottom emissiontype. In example embodiments, an optical distance controlling insulationlayer 350 may be disposed on the first electrode 300 in the firstsub-pixel region (I), the second sub-pixel region (II), and/or the thirdsub-pixel region (III). In this case, the optical distance controllinginsulation layer 350 may have substantially different thicknesses in thefirst, the second, and the third sub-pixel regions (I, II, and III).Therefore, first, second, and third optical resonance distances may beformed between the first electrode 300 and the second electrode 500 inthe first, the second, and the third sub-pixel regions (I, II, and III),respectively.

The light emitting structure 408 of the display device may include afirst hole injection layer 410, a hole transfer layer 420, a firstorganic light emitting layer 430, a blocking member 440, a chargegeneration layer 450, a second hole injection layer 460, a secondorganic light emitting layer 480, an electron transfer layer 490, etc.The light emitting structure 408 may have a constitution substantiallythe same as or substantially similar to that of the light emittingstructure 400 described with reference to FIG. 1.

In example embodiments, the blocking member 440 may include an electronblocking layer. The electron blocking layer may be disposed between thecharge generation layer 450 and the first organic light emitting layer430 in the first sub-pixel region (I). The blocking member 440 may blocka movement of electrons from the charge generation layer 450 to thefirst organic light emitting layer 430 in the first sub-pixel region(I). The electrons may not be supplied to the first organic lightemitting layer 430 in the first sub-pixel region (I) because of theblocking member 440, so that the first organic light emitting layer 430in the first sub-pixel region (I) may not emit light.

In comparison with the display device described with FIG. 1, the displaydevice with reference to FIG. 6 may be changed into a bottom emissiontype depending on a material change of the first electrode 300 and thesecond electrode 500. Even though there may be a position change of thefirst electrode 300 and the second electrode 500, first, second, andthird optical resonances may be generated in the first, the second, andthe third sub-pixel regions (I, II, and III), and emission of blue lightmay be prevented or reduced by the blocking member 440 in the firstsub-pixel region so that the display device may ensure high purity ofcolors of light, improved color gamut of light, and high brightnesswithout a color filter.

FIGS. 7 to 14 are cross-sectional views illustrating a method ofmanufacturing a display device having a light emitting structure inaccordance with example embodiments. The display device obtained by themethod illustrated in FIGS. 7 to 14 may have a constructionsubstantially the same as or substantially similar to that of thedisplay device described with reference to FIG. 1. However, thoseordinary skilled in the art will understand that the method according toexample embodiments may be properly and easily modified to manufactureone of the liquid crystal display devices described with reference toFIGS. 3 to 6.

Referring to FIG. 7, a buffer layer 110 may be formed on a substrate100. The substrate 100 may be formed using a transparent insulationmaterial. The buffer layer 110 may be formed using an oxide, a nitride,an oxynitride, an organic insulation material, etc. These may be usedalone or in a combination thereof. The buffer layer 110 may be formed onthe substrate 100 by a chemical vapor deposition (CVD) process, a plasmaenhanced chemical vapor deposition (PECVD) process, a high densityplasma-chemical vapor deposition (HDP-CVD) process, a spin coatingprocess, a thermal oxidation process, a printing process, etc.

A switching structure may be formed on the buffer layer 110. In exampleembodiments, after forming a semiconductor layer 210 on the buffer layer110, a gate insulation layer 220 may be formed on the buffer layer 110to cover the semiconductor layer 210. The semiconductor layer 210 may beformed using silicon by a chemical vapor deposition process, a plasmaenhanced chemical vapor deposition process, a high density plasmachemical vapor deposition process, a spin coating process, a thermaloxidation process, a printing process, etc. The gate insulation layer220 may be formed using an oxide, an organic insulation material, etc.In this case, the gate insulation layer 220 may be conformally formedalong a profile of the semiconductor layer 210. The gate insulationlayer 220 may be formed by a sputtering process, a chemical vapordeposition process, an atomic layer deposition process, a high densityplasma-chemical vapor deposition process, a spin coating process, aprinting process, etc.

A gate electrode 231 may be formed on the gate insulation layer 220under which the semiconductor layer 210 may be located. The gateelectrode 231 may be formed using a metal, a metal nitride, a conductivemetal oxide, a transparent conductive material, etc. Further, the gateelectrode 231 may be formed by a sputtering process, a chemical vapordeposition process, an atomic layer deposition (ALD) process, a spincoating process, a vacuum evaporation process, a pulsed laser deposition(PLD) process, a printing process, etc. Impurities may be doped into thesemiconductor layer 210 using the gate electrode 220 as an implantationmask, so that a first impurity region 211 and a second impurity region215 may be formed at lateral portions of the semiconductor layer 210,respectively. Therefore, a central portion of the semiconductor layer210 may be defined as a channel region 213. For example, the first andthe second impurity regions 211 and 215 may be formed by an ionimplantation process. In example embodiments, while forming the gateelectrode 231, a gate line (not illustrated) may be formed on the gateinsulation layer 220. The gate line may extend on the gate insulationlayer 220 to contact the gate electrode 231.

An insulating interlayer 240 may be formed on the gate insulation layer220 to cover the gate electrode 231. The insulating interlayer 240 maybe formed using an oxide, a nitride, an oxynitride, an organicinsulation material, etc. The insulating interlayer 240 may be formed bya sputtering process, a chemical vapor deposition process, a plasmaenhanced chemical vapor deposition process, an atomic layer depositionprocess, a spin coating process, a vapor deposition process, a pulsedlaser deposition process, a printing process, etc. A source electrode233 and a drain electrode 235 may be connected to the first impurityregion 211 and the second impurity region 215, respectively. In exampleembodiments, a data line (not illustrated) may be formed on theinsulating interlayer 240. The data line may be formed together with thesource electrode 233 and the drain electrode 235. The data line mayextend on the insulating interlayer 240 to contact the source electrode233.

In the switching device illustrated in FIG. 7, the switching device mayhave a top gate structure in which the gate electrode 231 is disposedover the semiconductor layer 210, however, the scope of exampleembodiments of the present invention is not limited to such a structure.For example, the switching device may have a bottom gate structureincluding a gate electrode located below a semiconductor layer or anoxide semiconductor device including a semiconductor oxide layer servingas an active layer.

Referring now to FIG. 7, an insulation layer 250 may be formed on thesubstrate 100 to cover the switching device, so that the switchingstructure including the switching device and the insulation layer 250may be formed on the substrate 100. The insulation layer 250 may beformed using a transparent insulation material such as a transparentplastic, a transparent resin, etc. Further, the insulation layer 250 maybe formed by a spin coating process, a printing process, a vacuumevaporation process, etc. In example embodiments, an upper portion ofthe insulation layer 250 may be partially removed by a planarizationprocess such as a chemical mechanical polishing process and/or anetch-back process. In some example embodiments, the insulation layer 250may be formed using a material having a self planarizing property, andthus the insulation layer 250 may have a substantially flat upper faceor surface.

Referring to FIG. 8, the insulation layer 250 may be partially removedto form a hole (not illustrated) that may partially expose the drainelectrode 235. For example, the hole through the insulation layer 250may be obtained by a photolithography process. In example embodiments,after a first conductive layer (not illustrated) filling the hole of theinsulation layer 250 is formed on the insulation layer 250, the firstconductive layer may be patterned to form the first electrode 300.Therefore, the first electrode 300 may be directly connected to thedrain electrode 235 exposed by the hole. The first conductive layer maybe formed on the insulation layer 250 by a sputtering process, aprinting process, a spray process, a chemical vapor deposition process,an atomic layer deposition process, a vacuum evaporation process, apulsed laser deposition process, etc. Further, the first electrode 300may be formed using a metal, an alloy, a transparent conductivematerial, etc. In example embodiments, the first electrode 300 may serveas a reflective electrode, a transparent electrode, a transflectiveelectrode depending on the materials. In some example embodiments, aftera contact (not illustrated), a pad (not illustrated), or a plug (notillustrated) is formed on the drain electrode 235 to fill the hole inthe insulation layer 250, the first electrode 300 may be formed on theinsulation layer 250 and on the contact, the pad, or the plug. In thiscase, the first electrode 300 may be electrically connected to the drainelectrode 235 through the contact, the pad, or the plug.

In example embodiments, an optical distance controlling insulation layer350 may be formed on the first electrode 300 by a laser induced thermalimaging process. In this case, the optical distance controllinginsulation layer 350 (see FIG. 13) may be formed in the second sub-pixelregion (II).

As illustrated in FIG. 9, a donor substrate 600 may be disposed abovethe substrate 100 having the first electrode 300. In this case, afterthe substrate 100 having the first electrode 300 is fixed using asupporting member (not illustrated), the donor substrate 600 may bealigned with respect to the substrate 100. The donor substrate 600 mayinclude a plurality of layers disposed on a base substrate 610. Inexample embodiments, the donor substrate 600 may include a light-to-heatconversion (LTHC) layer 620 disposed on the base substrate 610 and atransfer layer 630 located on the light-to-heat conversion layer 620.Here, the transfer layer 630 of the donor substrate 600 may be used toform the optical distance controlling insulation layer 350. For example,the transfer layer 630 may be formed using a benzocyclobutene-basedresin, an olefin-based resin, a polyimide-based resin, an acryl-basedresin, a polyvinyl-based resin, a siloxane-based resin, etc. These maybe used alone or in a combination thereof.

Referring to FIG. 10, the transfer layer 630 may be laminated on thefirst electrode 300 and the insulation layer 250 by contacting the donorsubstrate 600 with the substrate 100 and pressurizing the donorsubstrate 600 using a pressurizing member 640. For example, thepressurizing member 640 may include a roller, a crown press, etc. Insome example embodiments, the donor substrate 600 may be pressurizedusing gases without an additional pressurizing member, so that thetransfer layer 630 may be laminated on the first electrode 300 and theinsulation layer 250.

Referring to FIG. 11, a laser irradiation apparatus irradiates a laserbeam (indicated using arrows) to the donor substrate 600 in the secondsub-pixel region (II). In this case, the light-to-heat conversion layer620 converts energy of the laser beam to thermal energy. Therefore, inthe second sub-pixel region (II), adhesive strength between the transferlayer 630 and the first electrode 300 may be substantially larger thanthat between the transfer layer 630 and the light-to-heat conversionlayer 620 because of the thermal energy. In the laser induced thermalimaging process according to example embodiments, a high resolutionpattern may be obtained with a relatively low cost compared to aconventional thin film formation process using a mask.

Referring to FIG. 12, the donor substrate 600 is removed from thesubstrate 100 to form the optical distance controlling insulation layer350 in the second sub-pixel region (II). In example embodiments, thedonor substrate 600 may be removed by arranging an air blowing apparatus(not illustrated) adjacent to the donor substrate 600, and blowing gasesto an edge portion of the donor substrate 600.

In example embodiments, the optical distance controlling insulationlayer 350 may be formed on the first electrode 300 in the firstsub-pixel region (I) (see FIG. 13) by a laser induced thermal imagingprocess that is substantially the same as or substantially similar tothe laser induced thermal imaging process described with reference toFIGS. 10 to 12. In this case, a thickness of the optical distancecontrolling insulation layer 350 may vary depending on a thickness ofthe transfer layer 630 of the donor substrate 600. Therefore, theoptical distance controlling insulation layer 350 may have substantiallydifferent thicknesses in the first sub-pixel region (I) and the secondsub-pixel region (II). In some example embodiments, the optical distancecontrolling insulation layer 350 may be formed on the first electrode inthe third sub-pixel region (III) (see FIG. 13) by a laser inducedthermal imaging process that is substantially the same as orsubstantially similar to the laser induced thermal imaging processdescribed with reference to FIGS. 10 to 12.

Referring to FIG. 13, a protection layer 280 may be formed on theinsulation layer 250 in the non-display region of the display device.Here, the protection layer 280 may extend on a portion of the firstelectrode 300 in the display region of the display device. Theprotection layer 280 may be formed using an oxide, a nitride, anoxynitride, an organic insulation material, etc. Further, the protectionlayer 280 may be formed by a chemical vapor deposition process, a spincoating process, a plasma enhanced chemical vapor deposition process, avacuum evaporation process, a printing process, etc.

A light emitting structure 400 may be formed on the substrate 100 havingthe optical distance controlling insulation layer 350 and the protectionlayer 280. In example embodiments, the light emitting structure 400 maybe formed by sequentially forming a first hole injection layer 410, ahole transfer layer 420, a first organic light emitting layer 430, ablocking member 440, a charge generation layer 450, a second holeinjection layer 460, a second organic light emitting layer 480, and anelectrode transfer layer 490 on the optical distance controllinginsulation layer 350, the first electrode 300, and the protection layer280. In example embodiments, the first organic light emitting layer 430and the second organic light emitting layer 480 may be formed only inthe display region, and the blocking member 440 may be formed on thefirst organic light emitting layer 430 in the first sub-pixel region(I). The first hole injection layer 410, the hole transfer layer 420,the first organic light emitting layer 430, the second hole injectionlayer 460, the second organic light emitting layer 480, and the electrontransfer layer 490 including an organic material may be formed by avacuum evaporation process, a printing process, a spin coating process,a laser induced thermal imaging process, etc. The charge generationlayer 450 including a metal and/or a metal oxide may be formed by asputtering process, a printing process, a spray process, a chemicalvapor deposition process, etc. The blocking member 440 including anelectron blocking layer or an exciton quenching layer may be formed onthe first organic light emitting layer 430 by a laser induced thermalimaging process that is substantially the same as or substantiallysimilar to the laser induced thermal imaging process described withreference to FIGS. 10 to 12.

Referring to FIG. 14, a second electrode 500 may be formed on theelectron transfer layer 490. The second electrode 500 may be formedusing a metal, an alloy, and/or a transparent conductive material by asputtering process, a printing process, a spray process, a chemicalvapor deposition process, a vacuum evaporation process, an atomic layerdeposition process, etc.

According to example embodiments, a display device having a lightemitting structure may ensure an improved purity of colors of lightwithout a color filter, a manufacturing cost of the display device maybe reduced, and manufacturing processes of the display device may besimplified. The display device having various emission types such as abottom emission type, a top emission type, or a dual emission type maybe employed in various electronic and electric apparatuses such astelevisions, mobile communication apparatuses, monitors, MP3 players,portable display apparatuses, etc.

The foregoing is illustrative of example embodiments of the presentinvention, and is not to be construed as limiting thereof. Although afew example embodiments have been described, those skilled in the artwill readily appreciate that many modifications are possible in theexample embodiments without materially departing from the novelteachings of example embodiments. Accordingly, all such modificationsare intended to be included within the scope of example embodiments asdefined in the claims and their equivalents. In the claims,means-plus-function clauses are intended to cover the structuresdescribed herein as performing the recited function, and not onlystructural equivalents, but also equivalent structures.

1. A light emitting structure having a first sub-pixel region, a secondsub-pixel region, and a third sub-pixel region, comprising: a first holeinjection layer; a first organic light emitting layer on the first holeinjection layer; a charge generation layer on the first organic lightemitting layer; a second hole injection layer on the charge generationlayer; a second organic light emitting layer on the second holeinjection layer; an electron transfer layer on the second organic lightemitting layer; and a blocking member at at least one of the firstsub-pixel region, the second sub-pixel region, or the third sub-pixelregion.
 2. The light emitting structure of claim 1, wherein a firstoptical resonance distance in the first sub-pixel region, a secondoptical resonance distance in the second sub-pixel region, and a thirdoptical resonance distance in the third sub-pixel region, are differentfrom one another.
 3. The light emitting structure of claim 2, furthercomprising: an optical distance controlling insulation layer at at leastone of the first sub-pixel region, the second sub-pixel region, or thethird sub-pixel region.
 4. The light emitting structure of claim 3,wherein the optical distance controlling insulation layer is under thefirst hole injection layer.
 5. The light emitting structure of claim 3,wherein the optical distance controlling insulation layer has differentthicknesses in adjacent sub-pixel regions.
 6. The light emittingstructure of claim 3, wherein the optical distance controllinginsulation layer comprises a material that is the same as that of thefirst hole injection layer.
 7. The light emitting structure of claim 3,wherein the first optical resonance distance is adjusted to generate anoptical resonance for red light emitted from the first organic lightemitting layer or the second organic light emitting layer, the secondoptical resonance distance is adjusted to generate an optical resonancefor green light emitted from the first organic light emitting layer orthe second organic light emitting layer, and the third optical resonancedistance is adjusted to generate an optical resonance for blue lightemitted from the first organic light emitting layer or the secondorganic light emitting layer.
 8. The light emitting structure of claim7, wherein the first organic light emitting layer comprises a blue-lightemitting film, and wherein the second organic light emitting layercomprises a green-light emitting film and a red-light emitting film, ora single light emitting film adapted to emit green light and red light.9. The light emitting structure of claim 8, wherein the blocking memberis between the charge generation layer and the first organic lightemitting layer at the first sub-pixel region, the blocking member beingadapted to block a movement of electrons from the charge generationlayer to the first organic light emitting layer at the first sub-pixelregion.
 10. The light emitting structure of claim 8, wherein theblocking member is between the first hole injection layer and the firstorganic light emitting layer at the first sub-pixel region, the blockingmember being adapted to block a movement of excitons generated from thefirst organic light emitting layer at the first sub-pixel region. 11.The light emitting structure of claim 7, wherein the first organic lightemitting layer comprises a green-light emitting film and a red-lightemitting film, or a single light emitting film adapted to emit greenlight and red light, and wherein the second organic light emitting layercomprises a blue-light emitting film.
 12. The light emitting structureof claim 11, wherein the blocking member is between the electrontransfer layer and the second organic light emitting layer at the firstsub-pixel region, the blocking member being adapted to block a movementof electrons to the second organic light emitting layer at the firstsub-pixel region.
 13. The light emitting structure of claim 11, whereinthe blocking member is between the second hole injection layer and thesecond organic light emitting layer at the first sub-pixel region, theblocking member being adapted to block a movement of excitons generatedfrom the second organic light emitting layer at the first sub-pixelregion.
 14. The light emitting structure of claim 1, wherein theblocking member comprises an electron blocking layer or an excitonquenching layer.
 15. The light emitting structure of claim 14, theblocking member comprises at least one selected from the groupconsisting of fullerene, a polymer including substituted triarylamine, acarbazole based polymer,1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)cyclohexane (TAPC),1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)cyclopentane,4,4′-(9H-fluoren-9-ylidene)bis[N,N-bis(4-methylphenyl)-benzenamine,1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-4-phenylcyclohexane,1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-4-methylcyclohexane,1,1-Bis(4-(N,N-di-p-tolylamino)phenyl)-3-phenylpropane,Bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylpenyl)methane,Bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)ethane,4-(4-Diethylaminophenyl)triphenylmethane,4,4′-Bis(4-diethylaminophenyl)diphenylmethane,N,N-bis[2,5-dimethyl-4-[(3-methylphenyl)phenylamino]phenyl]-2,5-dimethyl-N′-(3-methylphenyl)-N′-phenyl-1,4-benzenediamine,4-(9H-carbazol-9-yl)-N,N-bis[4-(9H-carbazol-9-yl)phenyl]-benzenamine(TCTA),4-(3-phenyl-9H-carbazol-9-yl)-N,N-bis[4(3-phenyl-9H-carbazol-9-yl)phenyl]-benzenamine,9,9′-(2,2′-dimethyl[1,1′-biphenyl]-4,4′-diyl)bis-9H-carbazole(CDBP), 9,9′-[1,1′-biphenyl]-4,4′-diyl)bis-9H-carbazole (CBP),9,9′-(1,3-phenylene)bis-9H-carbazole (mCP),9,9′-(1,4-phenylene)bis-9H-carbazole,9,9′,9″-(1,3,5-benzenetriyl)tris-9H-carbazole,9,9′-(1,4-phenylene)bis[N,N,N′,N′-tetraphenyl-9H-carbazole-3,6-diamine,9-[4-(9H-carbazol-9-yl)phenyl]-N,N-diphenyl-9H-carbazol-3-amine,9,9′-(1,4-phenylene)bis[N,N-diphenyl-9H-carbazol-3-amine,9-[4-(9H-carbazol-9-yl)phenyl]-N,N,N′,N′-tetraphenyl-9H-carbazole-3,6-diamine,and 9-phenyl-9H-carbazol.
 16. A display device comprising: a substratehaving a first sub-pixel region, a second sub-pixel region, and a thirdsub-pixel region; a first electrode on the substrate; a light emittingstructure on the first electrode, the light emitting structurecomprising a blocking member at at least one of the first sub-pixelregion, the second sub-pixel region, or the third sub-pixel region; anda second electrode on the light emitting structure, wherein a firstoptical resonance distance between the first electrode and the secondelectrode at the first sub-pixel region, a second optical resonancedistance between the first electrode and the second electrode at thesecond sub-pixel region, and a third optical resonance distance betweenthe first electrode and the second electrode at the third sub-pixelregion are different from one another.
 17. The display device of claim16, wherein the light emitting structure comprises: a first holeinjection layer on the first electrode; a first organic light emittinglayer on the first hole injection layer; a charge generation layer onthe first organic light emitting layer; a second hole injection layer onthe charge generation layer; a second organic light emitting layer onthe second hole injection layer; and an electron transfer layer on thesecond organic light emitting layer.
 18. The display device of claim 17,wherein the light emitting structure further comprises an opticaldistance controlling insulation layer on the first electrode, theoptical distance controlling insulation layer having differentthicknesses in adjacent sub-pixel regions.
 19. The display device ofclaim 17, wherein the first optical resonance distance is adjusted togenerate an optical resonance for red light emitted from the firstorganic light emitting layer or the second organic light emitting layer,the second optical resonance distance is adjusted to generate an opticalresonance for green light emitted from the first organic light emittinglayer or the second organic light emitting layer, and the third opticalresonance distance is adjusted to generate an optical resonance for bluelight emitted from the first organic light emitting layer or the secondorganic light emitting layer.
 20. The display device of claim 19,wherein the first organic light emitting layer comprises a blue-lightemitting film, and wherein the second organic light emitting layercomprises a green-light emitting film and a red-light emitting film, ora single light emitting film adapted to emit green light and red light.21. The display device of claim 20, wherein the blocking member isbetween the charge generation layer and the first organic light emittinglayer at the first sub-pixel region, the blocking member being adaptedto block a movement of electrons from the charge generation layer to thefirst organic light emitting layer at the first sub-pixel region. 22.The display device of claim 20, wherein the blocking member is betweenthe first hole injection layer and the first organic light emittinglayer at the first sub-pixel region, the blocking member being adaptedto block a movement of excitons generated from the first organic lightemitting layer at the first sub-pixel region.
 23. The display device ofclaim 19, wherein the first organic light emitting layer comprises agreen-light emitting film and a red-light emitting film, or a singlelight emitting film adapted to emit green light and red light, andwherein the second organic light emitting layer comprises a blue-lightemitting film.
 24. The display device of claim 23, wherein the blockingmember is between the electron transfer layer and the second organiclight emitting layer at the first sub-pixel region, the blocking memberbeing adapted to block a movement of electrons to the second organiclight emitting layer at the first sub-pixel region.
 25. The displaydevice of claim 23, wherein the blocking member is between the secondhole injection layer and the second organic light emitting layer at thefirst sub-pixel region, the blocking member being adapted to block amovement of excitons generated from the second organic light emittinglayer at the first sub-pixel region.
 26. A method of manufacturing adisplay device, comprising: forming a first electrode on a substrate,the substrate having a first sub-pixel region, a second sub-pixelregion, and a third sub-pixel region; forming a light emitting structureon the first electrode, the light emitting structure comprising anoptical distance controlling insulation layer and a blocking member; andforming a second electrode on the light emitting structure, wherein afirst optical resonance distance between the first electrode and thesecond electrode at the first sub-pixel region, a second opticalresonance distance between the first electrode and the second electrodeat the second sub-pixel region, and a third optical resonance distancebetween the first electrode and the second electrode at the thirdsub-pixel region are different from one another.
 27. The method of claim26, wherein the optical distance controlling insulation layer is formedat at least one of the first sub-pixel region, the second sub-pixelregion, or the third sub-pixel region.
 28. The method of claim 27,wherein forming the optical distance controlling insulation layercomprises forming the optical distance controlling insulation layer onthe first electrode by a laser induced thermal imaging process.
 29. Themethod of claim 28, wherein forming the optical distance controllinginsulation layer further comprises: laminating a donor substrate on thesubstrate; irradiating a laser beam to at least one region of the donorsubstrate, the at least one region of the donor substrate correspondingto at least one of the first, the second, and the third sub-pixelregions; and removing the donor substrate from the substrate.
 30. Themethod of claim 27, wherein forming the light emitting structure furthercomprises: forming a first organic light emitting layer on the opticaldistance controlling insulation layer; forming a charge generation layeron the first organic light emitting layer; and forming a second organiclight emitting layer on the charge generation layer.
 31. The method ofclaim 30, wherein the blocking member is between the optical distancecontrolling layer and the first organic light emitting layer at at leastone of the first sub-pixel region, the second sub-pixel region, or thethird sub-pixel region.
 32. The method of claim 31, wherein the blockingmember is formed by a laser induced thermal imaging process.
 33. Themethod of claim 32, wherein forming the blocking member furthercomprises: laminating a donor substrate on the substrate; irradiating alaser beam to at least one region of the donor substrate, the at leastone region of the donor substrate corresponding to at least one of thefirst sub-pixel region, the second sub-pixel region, or the thirdsub-pixel region; and removing the donor substrate from the substrate.34. The method of claim 30, wherein the blocking member is between thefirst organic light emitting layer and the charge generation layer at atleast one of the first sub-pixel region, the second sub-pixel region, orthe third sub-pixel region.
 35. The method of claim 30, wherein theblocking member is between the second organic light emitting layer andthe second electrode in at least one of the first sub-pixel region, thesecond sub-pixel region, or the third sub-pixel region.